In a long term evolution-advanced (Long Term Evolution, hereinafter referred to as LTE-A) system, a user equipment (User Equipment, hereinafter referred to as UE) needs to report some channel state information (Channel State Information, hereinafter referred to as CSI) to an eNodeB (hereinafter referred to as eNodeB). The CSI may include: a channel quality indicator (Channel Quality Indicator, hereinafter referred to as CQI), a precoding matrix indicator (Precoding Matrix Indicator, hereinafter referred to as PMI), and a rank indicator (Rank Indicator, hereinafter referred to as RI). The eNodeB may determine a modulation and coding scheme (Modulation and Coding Scheme, hereinafter referred to as MCS) used in downlink according to received channel state information. To satisfy an LTE-A requirement for supporting a peak data rate up to 1 Gbit/s, a carrier aggregation (Component Aggregation, hereinafter referred to as CA) technology is used as a method for extending system bandwidth in the Rel-10 of the LTE-A system. The main conception of the CA is to aggregate multiple component carriers (Component Carrier, hereinafter referred to as CC) into a carrier whose frequency is higher than 20 MHz, so as to support a high-speed data rate. In a CA scenario in the Rel-10, the maximum number of CCs is 5. Among multiple uplink CCs, only one uplink CC, that is, a main carrier, has a physical uplink control channel (Physical Uplink Control Channel, hereinafter referred to as PUCCH), and periodical CSI information needs to be reported on the PUCCH to ensure a low block error rate (Block Error Rate, hereinafter referred to as BLER).
In the prior art, when CSI of multiple downlink CCs need to be reported, the downlink CCs need to be sorted according to a priority. CSI of a downlink CC with a lower priority is dropped as a whole, and CSI of a downlink CC with a highest priority is reported on the PDCCH of one CC. In the prior art, the CSI of the downlink CC with a lower priority may not be reported in a long period and the reported CSI cannot reflect a channel state in a CA scenario accurately, which leads to low precision of reporting.